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Aura File Format for Satellite Atmospheric Chemistry Data

Summary

This technical note presents a file format for satellite atmospheric chemistry data. It is based upon the file format guidelines successfully adopted for NASA's Aura mission. These guidelines make use of the HDF5 library with HDF-EOS5 extensions.

Status

The Aura File Format for Satellite Atmospheric Chemistry Data was recommended for use in NASA Earth science data systems in May 2008.

NASA Earth Science Community Recommendations for Use

Strengths

The RFC provides comprehensive documentation of the data file format and organization agreed to and implemented by the Aura Instrument Teams, including:

Major HDF-EOS version (HDF-EOS V2.x and HDF-EOS V5.x are not interchangeable)

Organization of geolocation and data fields and attributes

Dimension names

Geolocation field names, data types and dimension ordering

Data field names, data types and dimension ordering

Units for geolocation and data fields

Attribute names, values and units

Weaknesses

Units specified in the RFC do not conform to the SI Convention for Representation, and in some cases, there are inconsistencies in units among the different data fields (e.g., squared items are sometimes with a superscript, sometimes with ^ and others inline (vmr2 or K2)). However the RFC reflects the actual data files produced, which will not be changed. Other instrument teams using the Aura File Format Guidelines are urged to consider using the SI Convention.

Applicability and Limitations

If by analogy HDF5 is considered the Database Server, then the Aura Guidelines are the tables, and columns and rows, of a particular, unique database. Other Missions/teams should have the freedom to create their own artifact (i.e., database or "profile") to take advantage of their domain knowledge. What may be missing is the system-level picture of how the databases/profiles are developed for other missions. Is this standard an artifact of Aura that can be re-used? For maximum benefit, should it be re-used or should the process by which it was created be re-used? It's no small accomplishment that this was actually agreed-to by such a large team. Note that the process by which the Aura guidelines were developed is the subject of RFC-018: Creating File Format Guidelines: The Aura Experience.